Class to abstract decoding different image formats. More...

#include <image_decoder.h>

Inheritance diagram for esphome::runtime_image::ImageDecoder:

Public Member Functions
	ImageDecoder (RuntimeImage *image, ImageFormat format)
	Construct a new Image Decoder object.

virtual	~ImageDecoder ()=default

ImageFormat	get_format () const
	Get the image format handled by this decoder.

bool	is_active () const
	Check if a decoding session is in progress (prepare() called, reset() not yet).

virtual void	reset ()
	Reset the decoder state, ending any decoding session.

virtual int	prepare (size_t expected_size)
	Initialize the decoder, starting a new decoding session.

virtual int	decode (uint8_t *buffer, size_t size)=0
	Decode a part of the image.

bool	set_size (int width, int height)
	Request the image to be resized once the actual dimensions are known.

void	draw (int x, int y, int w, int h, const Color &color)
	Fill a rectangle on the display_buffer using the defined color.

virtual bool	is_finished () const
	Check if the decoder has finished processing.

Protected Attributes
double	x_scale_ = 1.0

double	y_scale_ = 1.0

RuntimeImage *	image_

size_t	expected_size_ = 0

size_t	decoded_bytes_ = 0

const ImageFormat	format_

bool	active_ = false

bool	size_valid_ = true

Detailed Description

Class to abstract decoding different image formats.

Definition at line 34 of file image_decoder.h.

Constructor & Destructor Documentation

◆ ImageDecoder()

esphome::runtime_image::ImageDecoder::ImageDecoder	(	RuntimeImage *	image,
		ImageFormat	format )

inline

Construct a new Image Decoder object.

Parameters

image	The RuntimeImage to decode the stream into.
format	The image format this decoder handles.

Definition at line 42 of file image_decoder.h.

◆ ~ImageDecoder()

virtual esphome::runtime_image::ImageDecoder::~ImageDecoder ( )

virtualdefault

Member Function Documentation

◆ decode()

virtual int esphome::runtime_image::ImageDecoder::decode	(	uint8_t *	buffer,
		size_t	size )

pure virtual

Decode a part of the image.

It will try reading from the buffer. There is no guarantee that the whole available buffer will be read/decoded; the method will return the amount of bytes actually decoded, so that the unread content can be moved to the beginning.

Parameters

buffer	The buffer to read from.
size	The maximum amount of bytes that can be read from the buffer.

Returns: int The amount of bytes read. It can be 0 if the buffer does not have enough content to meaningfully decode anything, or negative in case of a decoding error.

Implemented in esphome::runtime_image::BmpDecoder, esphome::runtime_image::JpegDecoder, esphome::runtime_image::PngDecoder, and esphome::runtime_image::QoiDecoder.

◆ draw()

void esphome::runtime_image::ImageDecoder::draw	(	int	x,
		int	y,
		int	w,
		int	h,
		const Color &	color )

Fill a rectangle on the display_buffer using the defined color.

Will check the given coordinates for out-of-bounds, and clip the rectangle accordingly. In case of binary displays, the color will be converted to binary as well. Called by the callback functions, to be able to access the parent Image class.

Parameters

x	The left-most coordinate of the rectangle.
y	The top-most coordinate of the rectangle.
w	The width of the rectangle.
h	The height of the rectangle.
color	The fill color

Definition at line 19 of file image_decoder.cpp.

◆ get_format()

ImageFormat esphome::runtime_image::ImageDecoder::get_format ( ) const

inline

Get the image format handled by this decoder.

Definition at line 46 of file image_decoder.h.

◆ is_active()

bool esphome::runtime_image::ImageDecoder::is_active ( ) const

inline

Check if a decoding session is in progress (prepare() called, reset() not yet).

Definition at line 49 of file image_decoder.h.

◆ is_finished()

virtual bool esphome::runtime_image::ImageDecoder::is_finished ( ) const

inlinevirtual

Check if the decoder has finished processing.

This should be overridden by decoders that can detect completion based on format-specific markers rather than byte counts.

Reimplemented in esphome::runtime_image::BmpDecoder, and esphome::runtime_image::QoiDecoder.

Definition at line 121 of file image_decoder.h.

◆ prepare()

virtual int esphome::runtime_image::ImageDecoder::prepare ( size_t expected_size )

inlinevirtual

Initialize the decoder, starting a new decoding session.

Parameters

expected_size Hint about the expected data size (0 if unknown).

Returns: int Returns 0 on success, a {

See also: DecodeError} value in case of an error.

Reimplemented in esphome::runtime_image::PngDecoder.

Definition at line 71 of file image_decoder.h.

◆ reset()

virtual void esphome::runtime_image::ImageDecoder::reset ( )

inlinevirtual

Reset the decoder state, ending any decoding session.

Subclasses should override this method to reset any format-specific state. Buffers the next decode can reuse should be kept allocated to avoid heap churn.

Reimplemented in esphome::runtime_image::BmpDecoder, esphome::runtime_image::PngDecoder, and esphome::runtime_image::QoiDecoder.

Definition at line 56 of file image_decoder.h.

◆ set_size()

bool esphome::runtime_image::ImageDecoder::set_size	(	int	width,
		int	height )

Request the image to be resized once the actual dimensions are known.

Called by the callback functions, to be able to access the parent Image class.

Parameters

width	The image's width.
height	The image's height.

Returns: true if the image was resized, false otherwise.

Definition at line 11 of file image_decoder.cpp.

Field Documentation

◆ active_

bool esphome::runtime_image::ImageDecoder::active_ = false

protected

Definition at line 136 of file image_decoder.h.

◆ decoded_bytes_

size_t esphome::runtime_image::ImageDecoder::decoded_bytes_ = 0

protected

Definition at line 134 of file image_decoder.h.

◆ expected_size_

size_t esphome::runtime_image::ImageDecoder::expected_size_ = 0

protected

Definition at line 133 of file image_decoder.h.

◆ format_

const ImageFormat esphome::runtime_image::ImageDecoder::format_

protected

Definition at line 135 of file image_decoder.h.

◆ image_

RuntimeImage* esphome::runtime_image::ImageDecoder::image_

protected

Definition at line 132 of file image_decoder.h.

◆ size_valid_

bool esphome::runtime_image::ImageDecoder::size_valid_ = true

protected

Definition at line 137 of file image_decoder.h.

◆ x_scale_

double esphome::runtime_image::ImageDecoder::x_scale_ = 1.0

protected

Definition at line 130 of file image_decoder.h.

◆ y_scale_

double esphome::runtime_image::ImageDecoder::y_scale_ = 1.0

protected

Definition at line 131 of file image_decoder.h.

The documentation for this class was generated from the following files:

esphome/components/runtime_image/image_decoder.h
esphome/components/runtime_image/image_decoder.cpp

Public Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ ImageDecoder()

◆ ~ImageDecoder()

Member Function Documentation

◆ decode()

◆ draw()

◆ get_format()

◆ is_active()

◆ is_finished()

◆ prepare()

◆ reset()

◆ set_size()

Field Documentation

◆ active_

◆ decoded_bytes_

◆ expected_size_

◆ format_

◆ image_

◆ size_valid_

◆ x_scale_

◆ y_scale_